- North Dakota State University
- Blossom end rot can be fixed with proper watering, not more nutrients
- Plants need calcium, too, just like teeth and bones!
- You Can Find Calcium Everywhere
- How Calcium Affects The Soil
- Some Fertilizers Include Calcium As A Buffer
- Calcium & Chemical Interactions
- The Solubility Of Calcium
- Solubility Of Alkaline Substances
- How Does Calcium Help Plants?
- What Does Calcium Do For Plants?
- How To Add Calcium To Soil
- Calcium Can Be Absorbed Through Leaves
- Calcium Is A Universal Necessity
- Foliar Feeding With Calcium: How To Make Your Own Calcium Fertilizer
- Why Use Homemade Calcium Rich Foliar Spray?
- Homemade Calcium Rich Foliar Spray
- Other Methods for Making Calcium Spray for Plants
- 5 Reasons to Add Calcium Carbonate to Your Garden
- Correcting Soil pH
- Reducing Toxicity of Metals in the Soil
- Increasing the Efficacy of Other Nutrients
- Adding Magnesium
- In General
- Looking For Ways To Boost Soluble Calcium In Soils
- Selecting the Right Calcium Source for Your Soil
North Dakota State University
Many of us have a few tricks we’ve developed in growing a great garden. One trick is to put a scoop of Epsom salt into each hole when planting tomatoes. Some gardeners swear it prevents blossom end rot.
It’s time to debunk that myth. Epsom salt doesn’t stop blossom end rot—it leads to more of it.
Blossom end rot is caused by a deficiency of calcium. Epsom salt contains magnesium sulfate—no calcium at all.
Adding Epsom salt to the soil may create more rot since magnesium and calcium ions compete for uptake into the plant. The more magnesium in the soil, the less chance that calcium will be absorbed.
So what can we do to prevent blossom end rot?
Don’t focus on the soil. Most soils in ND have plenty of calcium.
Focus on watering. The uptake of calcium depends on the uptake of water.
Irrigate regularly. Avoid the extremes of waterlogged soil and droughty soil. Mulch to maintain consistent levels of moisture in the soil.
Cultivate shallowly. Don’t damage the roots of your vines. We need these roots to absorb calcium.
Avoid overfertilization, especially with ammoniacal nitrogen fertilizers (ammonium nitrate and most complete fertilizers such as 10–10–10). Ammonium competes with calcium for uptake. Calcium nitrate is a better choice.
Vines should be green but not lush. Lush vines are more likely to suffer rot since actively growing leaves take calcium from the vine before the fruits get it. As a general rule, don’t sidedress a vine until after its first fruits set. Pinch suckers.
Calcium sprays might (or might not) help. Mix 4 tablespoons of calcium nitrate per gallon of water. Spray fruits, not leaves, two to three times a week. The key time is when tomatoes are dime-sized or smaller.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Published in the NDSU Yard & Garden Report, June 8, 2016.
Sources: Joy, A. and B. Hudelson. 2005. Blossom end rot. Univ. of Wisconsin Fact Sheet XHT1140. Madison, WI.
Williamson, J. 2009. Blossom end rot of tomato—an update. Clemson University Home and Garden Information Center. Clemson, SC.
Photos were made available under Creative Commons licenses specified by the photographers: Tom Kalb, NDSU; Mark; and Paul Bachi, Univ. of Kentucky Research and Education Center, Bugwood.org.
Blossom end rot can be fixed with proper watering, not more nutrients
Question: I am sending you pictures of my tomatoes. They have some kind of disease, but the plant itself looks healthy. The plants were in a pot on my covered deck, so I watered them regularly and used Miracle-Gro for tomatoes. Can you tell me where I went wrong so I can correct my methods for next year?
Answer: Your tomatoes are showing classic signs of blossom end rot. The black, sunken cankers on the bottoms of the fruits are typical of this ailment. Thankfully, it’s easy to prevent. But first, it’s important to understand why your tomatoes developed it in the first place.
Blossom end rot is the result of a calcium deficiency within the growing fruit. If the plants cannot acquire enough calcium during fruit development, the base of the tomato will become discolored and mushy. However, the problem is usually not remedied by adding more calcium to the soil, as some people may think, but rather by making sure the plant is properly watered. Let me explain.
Unlike some other nutrients, calcium is acquired by a plant primarily through a process called “mass flow.” This means the nutrient can come into the plant only via the water absorbed by the roots. If there isn’t enough water coming into the plant, it can’t access enough calcium, even if there’s plenty of it in the soil, and the plant begins to show signs of a calcium deficiency.
Here in Western Pennsylvania, our soils typically have ample calcium, so soil calcium deficiencies are unusual in a garden setting. The calcium is in the soil; your plants just can’t access it unless they have ample and consistent water. The same goes for plants grown in pots, especially if they’re grown in a commercial potting soil with added fertilizer or potting soil mixed with compost. The calcium is there; your plants just aren’t getting it.
Because you mentioned that your pots were grown on a covered deck, they probably did not have regular access to rainwater, and the water you were adding via hose-end irrigation was not enough.
A few tips for next year that will help prevent blossom end rot:
1. Make sure each tomato plant is growing in a pot that holds a minimum of five gallons of potting soil. The bigger the pot, the bigger the root system and the healthier the plant. Each container also should have a drainage hole in the bottom.
2. Proper watering is not adding a little water to the pot every day. Proper watering is using a hose to thoroughly saturate the soil every two to four days. I add five or six gallons of water, at minimum, to each of my potted tomatoes every few days throughout the summer. This is very important, especially if your tomatoes are growing somewhere where rainwater can’t reach them. As long as the pot has a drainage hole and it isn’t sitting in a saucer of water, it’s nearly impossible to overwater them. Deeper, less-frequent irrigation is always better than adding a little bit of water every day.
3. As I mentioned earlier, if you planted your potted tomatoes in a commercial potting mix with fertilizer already included, there was ample calcium present. Miracle-Gro tomato fertilizer supplies nitrogen, phosphorous and potassium, but it does not contain calcium. I suggest you mix your potting soil next year half-and-half with compost (either purchased in bags or from your own pile). It has a blend of macro- and micronutrients and supports good tomato growth. Plus, it increases the water-holding capacity of the potting soil. Another option would be to mix a half-cup of organic-based, granular fertilizer into the potting soil-compost blend at the start of the season. Espoma’s Tomato-tone or Gardener’s Supply Co.’s Organic Tomato Fertilizer are two good choices.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is jessicawalliser.com.
Send your gardening or landscaping questions to [email protected] or The Good Earth, 503 Martindale St., Third Floor, D.L. Clark Building, Pittsburgh, PA 15212.
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Plants need calcium, too, just like teeth and bones!
Calcium is an alkaline material widely distributed in the earth. It is the fifth most abundant element (by mass), usually found in sedimentary rocks in the mineral forms of calcite, dolomite and gypsum. We often see it as marble or limestone, which is formed by calcium carbonate rock dissolved in water containing carbon dioxide. Stalactites are formed by a slowly dripping solution of calcium carbonate mixed with other minerals. The same calcium carbonate dissolved in water is what makes our drinking water “hard.”
Calcium is found in as many as 80 compounds sometimes called calcium salts such as calcium carbonate (lime), calcium phosphate (fertilizers), calcium sulfate (Plaster of Paris), calcium gluconate (vitamins), calcium chloride (ice removal), and others.
“Calcium perhaps plays more roles in the overall health of both the plant and the soil than any other nutrient. As Dr. Albrecht explains it in his volumes of research, if we get the calcium right in the soil, most of our work is done.”
Calcium for good plants!
Articles for related information:
Understanding Soil Testing
The Importance of Microbes in Soil
All living things need calcium, yet even though calcium is an abundant mineral, it often comes in a form not easily absorbed by consumers. This same goes with plants.
Although a bit of calcium exists in quality gardening soils, it is very often not “bioavailable” to the plants growing there.
What can you do to ensure that your plants contract plenty of calcium from the soil?
In this article, we will discuss various calcium sources and explain the ways in which calcium can affect plants.
We will also present some sound advice about soil amendments supporting the efficient delivery of calcium. Read on to learn more.
You Can Find Calcium Everywhere
Calcium exist in great amounts in different places. In fact, it is the fifth most abundant element. It is typically sourced as a mineral in gypsum, dolomite, and calcite.
It is copious in sedimentary rocks such as limestone and marble.
Calcium also appears in multiple compounds. Some of the most common include:
- Lime – Calcium Carbonate
- Plaster of Paris – Calcium Sulfate
- Various Fertilizers – Calcium Phosphate
- Vitamin Supplements – Calcium Gluconate
- Substances for Ice Removal – Calcium Chloride
Although calcium comes profusely in many forms, not all can be absorbed by people, animals, and plants.
How Calcium Affects The Soil
For plants to be healthy, they must have the basic element, calcium. This naturally occurring element is frequently used as a soil modification for altering pH levels.
When calcium is added to the soil, it works in combination with other elements to create a variety of chemicals, all of which affect other chemical interactions.
One common use of calcium is the mitigation of damage that is caused by fertilizer overuse.
Some Fertilizers Include Calcium As A Buffer
There are several ways in which soil pH is affected by the addition of calcium. Soil that has high calcium content usually has an alkaline pH.
Those possessing low calcium content are generally acidic. Alkaline soils with a pH value of 7.2 or higher cannot absorb calcium.
When this is the case, the excess calcium in the soil becomes combined with other elements and creates insoluble compounds.
Plants cannot absorb these compounds. Furthermore, plants can restrict and regulate intake of calcium to a narrow range.
This function limits the amount of benefit a plant can glean from increased levels of calcium in soil.
Calcium & Chemical Interactions
When there is more calcium than can be absorbed in the soil, the excess combines with other elements and creates insoluble compounds.
This results in a restriction of the availability of elements, such as iron, boron, and phosphorous, that are necessary for plants to thrive.
Additionally, any of the following elements in excess can inhibit calcium absorption:
Potassium, calcium and magnesium should co-exist in adequate proportions. An excess of any of these nutrients would dissolve others resulting to either calcium or magnesium deficiency and more.
Calcium, as an acidic element may be compounded with other elements to reduces its acidity before it gets mixed with the soil. This process is known as liming.
The combination of cal-mag and calcium supplements for plants make a good liming material which comes in different forms such as the crystalline calcium carbonates, also known as the calcitic limestone.
On the other hand, crystalline calcium-magnesium is commonly known as dolomite lime.
The Solubility Of Calcium
When soil is very acidic, with a pH level of 7 or below, cations (combinations of positive ions) of aluminum and iron have greater solubility.
This results in restricted calcium absorption as these ions combine with calcium molecules in the soil.
This is damaging because acidic soil generally has very low calcium levels. Interference by aluminum and iron cations only worsens this problem.
An effective solution is to add gypsum or calcium carbonate to the soil. This will increase both the calcium level and the pH level of the soil, making more calcium available for plants.
Solubility Of Alkaline Substances
If soil pH levels are high, excess calcium becomes combined with other chemicals that may be present. For example, calcium frequently combines with boron and phosphorous.
This hampers plants from being able to absorb these elements.
If there is too much boron or phosphorous in soil, plants may suffer from discolored leaves and stunted growth.
It is possible for boron and phosphorous to reach toxic levels in soil. When this is the case, an application of calcium can help prevent damage to plants.
How Does Calcium Help Plants?
Just as calcium helps people and animals build and maintain strong bones and teeth, it helps plants build and maintain strong cell walls.
Therefore, it is so important for quality, nutritious soil to be rich in calcium balanced properly with other elements – both biotic and abiotic.
Abiotic elements are non-living elements in an environment (e.g. sun, wind, and rain). These must be considered when determining the nutritional value of soil.
For example, rain/water is vital in the process of calcium uptake because sufficient water is necessary to carry calcium throughout the plant to provide nutrition.
If a plant receives too little water, it will also receive too little calcium. For this reason, if your plants are showing signs of calcium deficiency, you should first examine your watering schedule.
If it seems your plants are adequately watered, examine the condition of your soil and determine the steps needed to increase the availability of calcium to your plants.
What Does Calcium Do For Plants?
In addition to building strong cell walls to help your plants stand up straight and tall, calcium also carries other nutrients along with it by binding to them.
Additionally, it acts to counteract organic acids and alkali salts in the soil. In short, calcium is a very important vitamin supplement for your garden.
If your plants are deprived of calcium, they will suffer from growth problems. Furthermore, leaves may wither and turn brown.
This tomato plant problem manifest as blossom-end rot and shows up on pepper plants as well.
Other possible victims of blossom end rot due to lack of calcium include squash, cucumber, and melon fruits.
You may be able to reduce blossom end rot by giving plants the correct nutrient solution.
In celery, you will see “black heart.” In cabbage, calcium deficiency results in internal tip burn.
How To Add Calcium To Soil
Lime is an excellent supplement for adding calcium to soil.
Add eggshells to your compost heap to add calcium to soil.
Want big, tasty tomatoes?
Crushed eggshells planted with your tomato seedlings will give them a boost of calcium.
Some gardeners use half eggshells as starter cups for their seeds.
This is easy to do. Just place the half eggshells in an egg carton, add a bit of potting soil, and plant your seeds. Water as usual.
Transferring your seedlings in eggshells to your garden is very simple.
Just lift the shell from the carton, crush it just a bit, and plant it for beautiful, healthy tomato plants!
Calcium Can Be Absorbed Through Leaves
If you see signs of calcium deficiency in mature plants, you can boost calcium levels by spraying a calcium solution directly onto the plant.
Calcium can be absorbed through the plant’s leaves.
To use the foliar feeding method, mix a solution using a gallon of water and half an ounce or a full ounce of calcium nitrate or calcium chloride.
Spray this solution evenly over your plants. Take special care to be sure that new growth is well saturated.
Calcium Is A Universal Necessity
It’s easy to see that proper calcium levels are essential to a healthy, thriving garden.
Follow the advice presented here to make sure your plants are getting the proper dose of calcium and all the benefits it provides.
Foliar Feeding With Calcium: How To Make Your Own Calcium Fertilizer
Foliar feeding with calcium (the application of calcium rich fertilizer to the plants leaves) may make the difference between a bumper crop of tomatoes to fruit with blossom end rot, or gorgeous Granny Smith apples to bitter ones. Let’s learn more about making and using a calcium foliar spray on plants.
Why Use Homemade Calcium Rich Foliar Spray?
Calcium foliar spray lends necessary calcium to the plant, preventing leaf necrosis, short brown roots, fungal issues, weak stems and stunted growth (damping off). Making calcium spray for plants will increase cell division, an important component, especially in those rapid growers such as tomatoes, sweet potatoes, and corn.
While it is true that acidic soils have a reduced amount of calcium compared to more alkaline soils, pH is not a true reflection of the necessity for foliar feeding with calcium but may be used as a general guideline.
Homemade Calcium Rich Foliar Spray
While commercial calcium foliar sprays may be purchased, it may be less expensive and just as easy to make a homemade calcium rich foliar spray with ingredients already in the home or garden. If you are experiencing any of the plant symptoms above or have had your soil’s pH tested and it’s deficient in calcium, now is a good time to learn how to make your own calcium fertilizer.
Foliar Feeding with Calcium Rich Eggshells
Plants require a ratio of calcium and magnesium; when one goes up, the other goes down. Utilizing your compost, which is generally rich in calcium or can be amended with the addition of lime or eggshells, is one way to increase the calcium level in growing plants. Another way to accomplish this goal is by making calcium spray for plants with eggshells.
To make calcium spray for plants with eggshells, boil 20 eggs in a pan covered with 1 gallon of water. Bring to a rolling boil, then remove from heat and allow to cool for 24 hours. Strain the water of shell fragments and store in an airtight container in a cool, dark place.
Another way to make homemade calcium rich foliar spray is by filling a gallon jar with water and eggshells. Steep for one month, allowing the eggshells to dissolve and filter their essential nutrients into the liquid. To create your calcium foliar spray, mix 1 cup of the resulting solution with 1 quart of water and transfer to a spray bottle. This homemade calcium rich foliar spray is also rife with nitrogen and magnesium, phosphorus and collagen, which are all essential nutrients for healthy growth.
Foliar Feeding with Calcium Rich Seaweed
It’s not just for sushi anymore. Particularly rich in bromine and iodine, seaweed is also rich in nitrogen, iron, sodium and calcium! So, how to make your own calcium fertilizer out of seaweed?
Collect the seaweed (if legal to do so where you are) or buy at the garden store and rinse thoroughly. Chop up the seaweed and cover with 2 gallons of water in a bucket. Cover loosely, ferment for a few weeks, and then strain. Dilute 2/3 cup to one gallon of water to make a calcium foliar spray.
How to Make Your Own Calcium Fertilizer Out of Chamomile
Chamomile contains sources of calcium, potash and sulfur, and as such is good for preventing damping off and many other fungal issues. Pour 2 cups of boiling water over ¼ cup chamomile blossoms (or you can use chamomile tea). Let steep until cool, strain and place in spray bottle. This foliar solution will keep for one week.
Other Methods for Making Calcium Spray for Plants
Great for any number of things, Epsom salts contain magnesium and sulfur, and where there’s magnesium there is certainly a correlation to calcium. The magnesium content aids the plant in utilizing other nutrients, such as calcium, more effectively. Plants, such as roses, tomatoes and peppers, which require higher amounts of magnesium, benefit the most from this spray. The general recipe for using Epsom salt as a calcium foliar spray is 2 tbsp. salts to 1 gallon of water, but for the aforementioned, cut the Epsom salt to 1 tbsp to 1 gallon of water.
Antitranspirants can also be used in the amount of ½ tsp to 8 ounces of skim milk (or equal amount of prepared powdered milk) for foliar feeding with calcium. Antitranspirants can be purchased via a garden center and are usually made from natural oils such as those from pine trees. Be sure to flush the sprayer out with water when done.
And last but not least, I previously mentioned using one’s compost to enrich soils with nutrients. Compost tea can be made with one part of mature compost to two parts of water (this can be done with mulched weeds, herbs or pond weeds too). Let sit for about a week or two and then strain and dilute with water until it looks like a weak cup o’ tea. This makes a fine method of foliar feeding with calcium.
BEFORE USING ANY HOMEMADE MIX: It should be noted that anytime you use a home mix, you should always test it out on a small portion of the plant first to make sure that it will not harm the plant. Also, avoid using any bleach-based soaps or detergents on plants since this can be harmful to plants. In addition, it is important that a home mixture never be applied to any plant on a hot or brightly sunny day, as this will quickly lead to burning of the plant and its ultimate demise.
5 Reasons to Add Calcium Carbonate to Your Garden
Calcium carbonate, more commonly known as calcitic lime or garden lime, has long been a staple in garden, field, and lawn management. Many homeowners make annual applications based on the advice of other growers, professionals, or their own research.
Calcium carbonate is available as a powder or as a granular application. Powdered calcium carbonate works faster in the soil, but is more difficult to apply at a consistent rate. Conversely, pelletized forms are easier to apply, but take longer to break down and provide their benefits.
Feeling like your soil needs a hand? Calcium carbonate is beneficial for correcting several common garden problems, but it should only be used based on the results of soil analysis. It is possible that too much calcium carbonate will make your garden inhospitable for your plants.
Here are five different situations in which you can add calcium carbonate to the garden to improve the performance of your crops.
Correcting Soil pH
Calcium carbonate is an excellent product for raising the pH of soil. Most (not all!) plants do best in soils with a pH between 5.5 and 6.5. Calcium carbonate can be broadcast over and incorporated into soils in need of a dose of alkalinity.
For best and quickest results, it should be incorporated into the soil such as with a tiller, rather than just being allowed to sit on the soil’s surface. This should not just be done as a matter of course though; there are many regions where soils are typically alkaline and calcium carbonate should never be used.
As the name implies, calcium carbonate is a great source of calcium (Ca). Calcium is an important nutrient that strengthens a plant’s cellular walls and is vital in new cell development. A calcium deficiency can lead to common fruit diseases such as blossom-end rot, which is prevalent in tomatoes and peppers.
If a soil analysis determines that a soil is deficient in calcium, but has a pH over 7.0, another source of calcium should be used, such as gypsum, which will not raise the soil pH but still provide the needed Ca.
Read More: The Top 4 Reasons Why Your Hydroponic System’s Nutrient Solution is Out of Whack
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Reducing Toxicity of Metals in the Soil
One role of calcium carbonate known to many professionals, but that is not necessarily common knowledge to the average home gardener, is its ability to mitigate heavy metals in the soil.
This is usually only a prescribed course of action if a soil analysis indicates that heavy metals are present in the soil at levels that can be remediated; if the levels are too high, removal of the soil would be the likely solution.
Besides being potentially toxic for humans, heavy metals can be toxic to plants as well. Calcium carbonate does not eliminate the metals from the soil, but “ties them up” so that they are not as available for uptake by plants.
Read More: The Presence and Transmission of Heavy Metals in Plant Fertilizers
Increasing the Efficacy of Other Nutrients
One of the many unseen benefits of using calcium carbonate, as it relates to its ability to adjust soil pH, is its role in making nutrients available to plants.
All of the nutrients that a plant needs may be present in a soil, but they may be unavailable to plants (see Nutrient Lockout) if the pH is not conducive for the plant to easily “grab a hold” of. The majority of nutrients that a plant needs are most available to plants at the aforementioned 5.5 to 6.5 pH range.
Although it’s not evident in the name “calcium carbonate”, there is some magnesium (Mg) in this substance. It is sometimes found with or added to calcium carbonate and is a required element for plants. It is more often found in dolomitic lime as opposed to calcitic lime.
Magnesium is required for proper photosynthesis of plants as it is a component of chlorophyll molecules. As such, a plant that is in need of additional Mg will usually show signs of deficiency in its older, lower leaves. They will start to turn yellow between the veins, which will remain green.
In the absence of a site-specific prescription, calcium carbonate is generally applied to gardens and lawns in need of “sweetening” at a rate of one to two pounds (0.45 to 0.9 kg) per 100 square feet (9.3 square meters) of area. In the event of over-application or in soils that have a high pH, sulfur should be applied at the recommended rate.
Read More: How To Tel If Your Plants Have a Sulfur Deficiency
Looking For Ways To Boost Soluble Calcium In Soils
Is it time to begin to ‘rethink how we think’ about soil calcium, or do we just continue on with our old, conventional thinking that the soil has enough?
One of the ingredients in building the ‘perfect soil’ is routine application of gypsum, or calcium sulfate. My general practice is to apply 1 ton of synthetic gypsum every 3 or 4 years, and in some fields 300 to 400 pounds of pelletized gypsum annually.
But don’t expect to see immediate changes in tilth or soil health. Change takes time and it may take 5 or 6 years to notice.
Is More Better?
I’m a fan of gypsum and have realized its benefits, which include improved soil structure, nutrient benefits through added calcium and sulfur, and remediation of salinity and sodic soils.
But an overlooked factor, in my mind, is how additional calcium might benefit the soil and if we’re even measuring the right factors. Agronomists don’t track calcium and take it for granted that most soils already have plenty. I wonder if our thinking is wrong?
A routine soil test measures exchangeable calcium in parts per million (ppm). That is the calcium cation held on the soil exchange complex. Soils on our farm routinely measure about 3,000 to 4,000 ppm, so that is obviously a lot of calcium in the soil.
But I question how available it is to the soil, and if I’m getting the true benefit of calcium to improve soil structure — and if the crop is…
Selecting the Right Calcium Source for Your Soil
Calcium plays a vital role in plant growth, specifically cell wall formation, cell division and pollination. It also signals plants to respond to drought and heat stress, activates many plant enzyme systems and helps plants absorb other nutrients. Calcium also promotes healthy soil structure by loosening soils and stabilizing organic matter, which increases soil water- and nutrient-holding capacity.
When evaluating calcium needs on your farm, we recommend looking at three key factors on your soil test: Soil pH, cation exchange capacity (CEC) and percent base saturation of calcium.
Soil pH is a well understood concept in farming. When pH drops below 6.5, growers understand the need for liming materials to increase soil pH and improve nutrient availability.
A common misconception is if soil pH is above 6.5, you don’t need to apply calcium. However, regular calcium application is needed to maintain optimal soil health and plant performance.
Two common liming materials are calcitic lime (CaCO3) and dolomitic lime (CaMgCO3). While both contain calcium, the ability of lime to increase soil pH is actually a function of carbonate (CO3) in the lime. When applied to acidic soils, CO3 reacts and neutralizes acidity, effectively raising pH.
If lime is not needed to raise pH, apply calcium in a form crops can easily take up. Bio-Cal® or OrganiCal™ are both good options for bulk-application calcium sources. If precision application is desired, consider applying a granulated product like TerraNu Calcium™.
Cation Exchange Capacity
Cation exchange capacity (CEC) is a measure of soil’s capacity to hold nutrients. Soils with greater CECs can hold more nutrients, but this may not indicate plant availability. Without knowing CEC, it is difficult to make fertility recommendations because CEC indicates the soil’s potential for crop production.
Think of CEC like a dinner plate — the greater the CEC, the more nutrients the soil can hold.
Percent Base Saturation
Percent base saturation is the percentage of exchangeable potassium, magnesium, calcium, sodium and hydrogen in the soil (total = 100 percent). Growers should maintain a calcium percent base saturation level of 70 to 80 percent for optimum soil conditions and plant performance.
Calcium base saturation levels above 80 percent can mean you’re short on potassium or magnesium. If present, these deficiencies should be addressed through a fertility program. Recommended soil calcium levels as a function of CEC are summarized in Table 1.
There are multiple calcium products available on the market with varying quality, formulation and physical forms. Commonly applied calcium products and their features and benefits are outlined in Table 2. Once you’ve determined what soil or crop deficiencies you’ll address with your calcium program, selecting the right product becomes much simpler. Other factors, such as available application equipment and tillage methods, must also be taken into account.
Because calcium deficiencies can negatively impact almost every aspect of crop production, it’s important to frequently monitor soil calcium levels. Keep in mind that plant and soil calcium needs vary widely. To ensure plant availability of calcium all season, we recommend applying calcium products that contain multiple sources of calcium like Bio-Cal or OrganiCal for season-long availability. If additional sulfur and organic matter is needed, TerraNu Calcium is an excellent fit.